Betty and Bob borrow $850,000 at 12% per annum compounded monthly for a 20 year (fixed rate) mortgage. a. What is their monthly payment? b. How much interest will they pay over the 20 years? c. After 10 years how much equity will they have in their property, i.e. how much principal will they have paid? d. What will be the principal and interest components of the 120th payment? (I need a step-by-step explanation of the formulas used. Thanks)